In order to capture or analyze signal transmissions, it is often necessary to locate the transmission in time and frequency. In some cases, the time and frequency of the transmission are known for the signal. In other cases neither the time nor the frequency of the transmission is known a priori. For example, FIG. 1 illustrates a signal analyzer 110 operating in the presence of a plurality of signal transmitters 120, where neither the time nor the frequency of a transmission is known in advance. Illustratively, the signal transmitters 120 are push-to-talk (PTT) marine radios that transmit signals sporadically and, during extended periods of time, do not transmit signals. Because the time of commencement of signal transmissions and the frequencies of the signal transmissions are not known, in order for signal analyzer 110 to capture and analyze an entire signal transmission from one of the signal transmitters 120, the signal analyzer 110 must locate the time and frequencies of the signal transmission. This can impose significant processing demands on a processor in signal analyzer 110.
It would be desirable to provide an efficient means of triggering signal analysis on signal transmissions when neither the frequency nor the time of the signal transmission is known in advance.